Humankind is facing an imminent threat of extinction, according to new research released on Wednesday by the science journal Nature. The report Approaching a state shift in Earth’s biosphere reveals that our planet's biosphere is steadily approaching a 'tipping point', meaning all ecosystems are nearing sudden and irreversible change that will not be conducive to human life.

The authors describe what they see as a fast paced 'state shift' once the tipping point is reached, which contrasts with the mainstream view that environmental change will take centuries. "It's a question of whether it is going to be manageable change or abrupt change. And we have reason to believe the change may be abrupt and surprising," said co-researcher Arne Mooers, a professor of biodiversity at Simon Fraser University in Canada's British Columbia.

"The data suggests that there will be a reduction in biodiversity and severe impacts on much of what we depend on to sustain our quality of life, including, for example, fisheries, agriculture, forest products and clean water. This could happen within just a few generations," stated lead author Anthony Barnosky, a professor of integrative biology at the University of California in Berkeley.

"My colleagues who study climate-induced changes through the Earth's history are more than pretty worried," he said in a press release. "In fact, some are terrified," said co-researcher Arne Mooers, a professor of biodiversity at Simon Fraser University in Canada's British Columbia.

The report, written by 22 scientists from three continents ahead of this year's Rio+20 summit, claims that the 'state shift' is likely; however, humans may have a small window to curb over-consumption, over-population growth and environmental destruction, with drastic efforts to change the way we live on planet earth through international cooperation.

Climate change, population growth and environmental destruction could cause a collapse of the ecosystem just a few generations from now, scientists warned on Wednesday in the journal Nature.

The paper by 22 top researchers said a "tipping point" by which the biosphere goes into swift and irreversible change, with potentially cataclysmic impacts for humans, could occur as early as this century. [...]

The Nature paper, written by biologists, ecologists, geologists and palaeontologists from three continents, compared the biological impact of past episodes of global change with what is happening today.

The factors in today's equation include a world population that is set to rise from seven billion to around 9.3 billion by mid-century and global warming that will outstrip the UN target of two degrees Celsius (3.6 degrees Fahrenheit).

The team determined that once 50-90 percent of small-scale ecosystems become altered, the entire eco-web tips over into a new state, characterised especially by species extinctions.

Once the shift happens, it cannot be reversed.

To support today's population, about 43 percent of Earth's ice-free land surface is being used for farming or habitation, according to the study.

On current trends, the 50 percent mark will be reached by 2025, a point the scientists said is worryingly close to the tipping point.

If that happened, collapse would entail a shocking disruption for the world's food supply, with bread-basket regions curtailed in their ability to grow corn, wheat, rice, fodder and other essential crops.

"It really will be a new world, biologically, at that point," said lead author Anthony Barnosky, a professor of integrative biology at the University of California in Berkeley.

Or, as Canadian co-author Arne Mooers, at Simon Fraser Univeristy in British Columbia, puts it: "Once the shift occurs, they'll be no going back."

A shift or tipping point is "speculation at this point," Mooers told Postmedia News.

"But it's one of those things where you say: 'Hey, maybe we better find out,' because if it's true, it's pretty serious." [...]

The climate is warming so fast that the "mean global temperature by 2070 (or possibly a few decades earlier) will be higher than it has been since the human species evolved," they say.

And to support the current population of seven billion people, about 43 per cent of Earth's land surface has been converted to agricultural or urban use. The population is expected to hit nine billion by 2045 and they say current trends suggest that half Earth's land surface will be altered by humans by 2025.

That's "disturbingly close" to a potential global tipping point, Barnosky says in a release issued with the report. The study says tipping points tend to occur when 50 to 90 per cent of smaller ecosystems have been disrupted.

"I think that if we want to avoid the most unpleasant surprises, we want to stay away from that 50 per cent mark," Barnosky says.

The "ultimate effects" of a state shift are unknown, but the researchers suggest it could have severe impact on the world's fisheries, agriculture, forests and water resources. And they warn that "widespread social unrest, economic instability and loss of human life could result."

Barnosky and his colleagues reviewed research on climate change, ecology and Earth's tipping points that break the camel's back, so to speak. At certain thresholds, putting more pressure on the environment leads to a point of no return, Barnosky said. Suddenly, the planet responds in unpredictable ways, triggering major global transitions.

The most recent example of one of these transitions is the end of the last glacial period. Within not much more than 3,000 years, the Earth went from being 30 percent covered in ice to its present, nearly ice-free condition. Most extinctions and ecological changes (goodbye, woolly mammoths) occurred in just 1,600 years. Earth's biodiversity still has not recovered to what it was.

Today, Barnosky said, humans are causing changes even faster than the natural ones that pushed back the glaciers — and the changes are bigger.